pip9

Are ur compression numbers going to be lower until the rings seat? My numbers were around 180-200 after the break-in period. I never check the numbers right after a rebuild. I did tonite and the numbers were 145-150 across. I haven't driven the car or anything yet just ran it for like 20 mins. Is this normal?

B18C1CYA

did you change compression? and yes it should get higher , but when i built my motor mine didnt change much at all but i have good soild numbers, the rings will seat in 20 miles , but will be fully seated in 1000 miles

pip9

no, different pistons but same c/r. same type of headgasket and head i used before. I haven't driven it yet. It got too dark for me to put the suspension and wheels back together tonite. So once i drive it, then the numbers should go up. I literally started it up let it run for a few mins then did a compression check. I'm running the same fuel setup and boostedhybrid tuned. The spark plugs are black though. And i'm getting a weird idle after the car warms up.

B18C1CYA

wierd like how, it could be a air buble in the coolant at the iac valve doing that, but a valve adjustment not being done properly can make low numbers, btw what is your compression ratio? cus mine is 9:1 and i pull about 185psi and thats normal for that compression ratio on a b series.

pip9

The valves are adjusted fine. 9:1 c/r. I had 180-190 across the motor before. The coolant was bleed. the car starts up fine, 1500-2000 rpms cold start up then once it goes into closed loop it idles at ~500 rpms. If give it some gas it sounds fine again. My vacuum gauge reads ~18psi while at 1k-3k. When i let off the throttle it sits at 900-1100 at 18psi vacuum for a second or two then it dies off and goes to ~500 rpms and the vacuum goes to ~10psi. I guess i'll drive it around tomorrow and see what happens.

B18C1CYA

just put some miles on it your vacum #s will increase as the rings seat, thats definitly your problem cus your vac numbers are pritty low , they will be lower also because of lower compression but not that low,just put like 20 miles on it of just normal driving then i would start with low boost levels at first then work your way up, my motor had 24 miles on it and i was running 15psi and every thing is great runs awsome, your already tuned so it should be good to go, good luck with it

pip9

cool, i hope ur right. I'm sort of tuned. I was tuned up to 8psi with my other setup. This one is exactly the same except for its a new block, new pistons, and new rings. I still need to go back to get my high boost tuned. I just hope this head doesn't lift up on me like before (copper sprayed and torqued to 70ft/lbs this time). btw, my c/r is actually alot higher then 9:1 with the y8 head and headgasket. I think its around 10-10.2:1

B18C1CYA

hum those #s should get alot higher than cus the should be around 260psi or so after they are seated, well if the compression is higher then befor when it was tuned then dont boost on it at all get it retuned, you dont want to have all that hard work go down the *******.

pip9

no, the c/r is still the same as when it was tuned. I had the same setup.

B18C1CYA

ok good so boost away , jeff probly set your boost cut not to far past 8 psi so you cant hurt anything, well you should have no problem then just breakin and tune for more boost